Autonomous vehicles, such as vehicles that do not require a human driver, can be used to aid in the transport of passengers or items from one location to another. Such vehicles may operate in a fully autonomous mode where passengers may provide some initial input, such as a pickup or destination location, and the vehicle maneuvers itself to that location.
Robust operation of an autonomous vehicle or a vehicle operating in an autonomous driving mode requires proper response to unexpected circumstances, such as construction that alters the normal flow of traffic. In other words, the flow of traffic may be redirected temporarily due to construction or a traffic incident. For instance, lanes may be closed by blocking the lane with an object such as an emergency vehicle, construction sign, cones, barrels or other objects. At the same time, other lanes may remain open and/or cones or other markers have been used to create new corridors that separate new “lanes” or opposing traffic. In many instances, the features which mark the redirection, such as cones or emergency vehicles will not be previously recorded in the maps used by the vehicle's control computing devices to navigate the vehicle. Accordingly, for safe and effective control, identifying and responding to such circumstances is a critical function for these vehicles.